U.S. patent application number 12/601605 was filed with the patent office on 2010-07-08 for refrigeration cycle device.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Takeshi Hatomura, Masayuki Kakuda, Takashi Okazaki, Shin Sekiya, Mihoko Shimoji.
Application Number | 20100170295 12/601605 |
Document ID | / |
Family ID | 40074962 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100170295 |
Kind Code |
A1 |
Okazaki; Takashi ; et
al. |
July 8, 2010 |
REFRIGERATION CYCLE DEVICE
Abstract
In order to provide a refrigeration cycle device that is compact
and efficiently utilizing an expansion machine and reduced in
manufacturing cost through the use of a first compressor and second
compressor driven by an expansion machine, a heat radiator and an
on-off valve are disposed between the first and the second
compressors and the second heat radiator is utilized irrespective
of the operating mode such as the cooling or heating operation.
Also, the heat transfer area ratio, which is a ratio of the heat
transfer area of the second heat source side heat exchanger
relative to the total heat transfer area of the heat transfer areas
of said first and second heat source side heat exchangers, is set,
according to the air speed distribution, within a range at which
the COP is at its peak. Thus, the second heat source side heat
exchanger can be utilized even during the heating operation,
providing a high efficiency refrigeration cycle device.
Inventors: |
Okazaki; Takashi; (Tokyo,
JP) ; Shimoji; Mihoko; (Tokyo, JP) ; Sekiya;
Shin; (Tokyo, JP) ; Kakuda; Masayuki; (Tokyo,
JP) ; Hatomura; Takeshi; (Tokyo, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Chiyoda-ku, Tokyo
JP
|
Family ID: |
40074962 |
Appl. No.: |
12/601605 |
Filed: |
May 22, 2008 |
PCT Filed: |
May 22, 2008 |
PCT NO: |
PCT/JP2008/059461 |
371 Date: |
December 18, 2009 |
Current U.S.
Class: |
62/510 ;
418/55.1; 62/513 |
Current CPC
Class: |
F25B 2313/02742
20130101; F25B 9/06 20130101; F04C 18/0215 20130101; F25B 2600/17
20130101; F25B 29/006 20130101; F25B 2313/0253 20130101; F25B
2700/21152 20130101; F25B 13/00 20130101; F25B 1/10 20130101; F25B
2400/14 20130101; F25B 2309/061 20130101; F25B 2700/2106 20130101;
F04C 23/001 20130101 |
Class at
Publication: |
62/510 ; 62/513;
418/55.1 |
International
Class: |
F25B 1/10 20060101
F25B001/10; F25B 41/00 20060101 F25B041/00; F01C 1/02 20060101
F01C001/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2007 |
JP |
2007-139472 |
Mar 28, 2008 |
JP |
2008-086345 |
Claims
1. A refrigeration cycle device comprising a first compressor, a
second compressor driven by recovered power recovered by an
expansion machine, refrigerant flow path changeover means, a load
side heat exchanger, a first heat source side heat exchanger and a
second heat source side heat exchanger, and changeable between a
cooling operation and a heating operation by said refrigerant flow
path change-over means; wherein said second compressor and said
first compressor are connected in series; said second heat source
side heat exchanger is disposed between said first compressor and
said second compressor during the cooling operation, and wherein
the operation is performed by the utilization of said first heat
source side heat exchanger and said second heat source side heat
exchanger irrespective of operation mode.
2. A refrigeration cycle device as claimed in claim 1, wherein an
inlet portion of said first heat source side heat exchanger and an
inlet portion of said second heat source side heat exchanger as
well as an outlet portion of said first heat source side heat
exchanger and an outlet portion of said second heat source side
heat exchanger are respectively connected therebetween by a pipe
having an on-off valve.
3. A refrigeration cycle device as claimed in claim 2, wherein said
on-off valve is a check valve.
4. A refrigeration cycle device comprising a first compressor, a
second compressor driven by recovered power recovered by an
expansion machine, refrigerant flow path changeover means, a load
side heat exchanger, a first heat source side heat exchanger and a
second heat source side heat exchanger, and changeable between a
cooling operation and a heating operation by said refrigerant flow
path changeover means; wherein said second compressor and said
first compressor are connected in series; said second heat source
side heat exchanger is disposed between said first compressor and
said second compressor during the cooling operation, and wherein
heat transfer area ratio, which is a ratio of the heat transfer
area of the second heat source side heat exchanger relative to the
total heat transfer area of the heat transfer areas of said first
and second heat source side heat exchangers provided on the high
pressure side, is made 0.2-0.6.
5. A refrigeration cycle device, wherein an indoor unit
self-containing a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, and a plurality
of indoor units self-containing a load side heat exchanger and an
on-off valve are connected by a pipe, and said plurality of indoor
units are independently changeable between a cooling operation and
a heating operation; wherein said second compressor and said first
compressor are connected in series; said second heat source side
heat exchanger is disposed between said first compressor and said
second compressor during the cooling operation, and wherein the
operation is performed by the utilization of said first heat source
side heat exchanger and said second heat source side heat exchanger
irrespective of the operation modes of said indoor units.
6. A refrigeration cycle device as claimed in claim 5, wherein said
refrigeration circuit has four operation modes of full cooling
operation, cooling dominant operation, full heating operation and
heating dominant operation, and power recovery by an expansion
machine is performed only during the full cooling operation.
7. A refrigeration cycle device as claimed in claim 5, wherein a
bypass flow path for bypassing said second compressor is provided
and an on-off valve is provided in the bypass flow path.
8. A refrigeration cycle device as claimed in claim 5, wherein said
second compressor comprises a vessel for containing a second
compression mechanism, a second compression suction pipe disposed
in said vessel, a second compression discharge port communicated to
a second compression chamber via a second compression discharge
valve and opening to a second compression discharge pressure space
within said vessel, a second compression discharge pipe disposed in
said vessel to open to said second compression discharge pressure
space, and a bypass pipe connected at one end to the second
compression suction pipe at the outside of said vessel and at the
other end to said vessel, said bypass pipe having an on-off valve
disposed therein.
9. A refrigeration cycle device as claimed in claim 5, wherein said
expansion machine and said second compressor are both of an
integral structured scroll-type.
10. A refrigeration cycle device as claimed in claim 5, wherein the
volume ratio of the displacement volume of said expansion machine
and the displacement volume of said second compressor is
1.5-2.5.
11. A refrigeration cycle device as claimed in claim 5, wherein an
on-off valve disposed at the inlet portion of said expansion
machine and having an adjustable degree of opening as well as an
on-off valve bypassing said expansion machine and having an
adjustable degree of opening are provided, and wherein said both
on-off valves are controlled to control the temperature or the
pressure from the outlet of said second compressor to the inlet of
said expansion machine.
12. A refrigeration cycle device as claimed in claim 11, wherein
said both on-off valves are controlled with the operated value
operated on the basis of the detected value of said temperature or
said pressure used as a target value.
13. A refrigeration cycle device as claimed in claim 12, wherein at
least one of said first heat source side heat exchanger and said
second heat source side heat exchanger is constituted by a
plurality of heat exchangers.
14. A refrigeration cycle device as claimed in claim 13, wherein at
least one of the heat transfer area and the heated medium of said
first heat source side heat exchanger or said second heat source
side heat exchanger is controlled in response to environmental
conditions.
15. A refrigeration cycle device as claimed in claim 14, wherein
said environmental conditions includes at least one of the outdoor
air temperature, the air conditioner load and the indoor air
temperature.
16. A refrigeration cycle device as claimed in claim 5, wherein
carbon dioxide is used as a refrigerant.
17. A refrigeration cycle device comprising a first compressor, a
second compressor driven by recovered power recovered by an
expansion machine, refrigerant flow path changeover means, a load
side heat exchanger, a first heat source side heat exchanger and a
second heat source side heat exchanger; wherein said first
compressor and said second compressor are connected in series in a
refrigerant flow path; said second heat source side heat exchanger
is disposed in a flow path between said first compressor and said
second compressor during the cooling operation; said first heat
source side heat exchanger and said second heat source side heat
exchanger during the cooling operation are in an integral structure
or in a divided structure so that fins are not common in the
direction of column; and wherein heat transfer area ratio, which is
a ratio of the heat transfer area of the second heat source side
heat exchanger relative to the total heat transfer area of the heat
transfer areas of said first and second heat source side heat
exchangers, is set, according to the air speed distribution, with
the air speed distributions of said first and second heat source
side heat exchanger taken into consideration, within a range
including a point at which the COP is at a maximal.
18. A refrigeration cycle device as claimed in claim 17, wherein a
fan is disposed at a position higher than the heat exchanger, and
said second heat source side heat exchanger is disposed at a
position higher than said first heat source side heat exchanger,
and said heat transfer area ratio is set at 0.13-0.45.
19. A refrigeration cycle device as claimed in claim 17, wherein a
fan is disposed at a position higher than the heat exchanger, and
said second heat source side heat exchanger is disposed at a
position lower than said first heat source side heat exchanger, and
said heat transfer area ratio is set at 0.32-0.60.
20. A refrigeration cycle device comprising a first compressor, a
second compressor driven by recovered power recovered by an
expansion machine, refrigerant flow path changeover means, a load
side heat exchanger, a first heat source side heat exchanger and a
second heat source side heat exchanger; wherein said first
compressor and said second compressor are connected in series in a
refrigerant flow path; said second heat source side heat exchanger
is disposed in a flow path between said first compressor and said
second compressor during the cooling operation; said first heat
source side heat exchanger and said second heat source side heat
exchanger during the cooling operation are in an integral structure
or in a divided structure so that fins are not common in the
direction of column; and wherein a fan is disposed above or beside
of the heat exchanger and said second heat source side heat
exchanger is disposed down stream side of said first heat source
side heat exchangers.
22. A refrigeration cycle device, wherein an indoor unit
self-containing a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, and a plurality
of indoor units self-containing a load side heat exchanger and an
on-off valve are connected by a pipe, and said plurality of indoor
units are independently changeable between a cooling operation and
a heating operation; wherein said second compressor and said first
compressor are connected in series in a refrigerant flow path; said
second heat source side heat exchanger is disposed in a flow path
between said first compressor and said second compressor during the
cooling operation, and wherein the operation is performed by the
utilization of said first heat source side heat exchanger and said
second heat source side heat exchanger irrespective of the
operation modes of said indoor units.
23. A refrigeration cycle device as claimed in claim 21, wherein a
refrigerant that is generally used in a super critical condition is
used as a refrigerant.
Description
TECHNICAL FIELD
[0001] This invention relates to a refrigeration cycle device
utilizing a super critical fluid and, more particularly, to a
refrigeration cycle device utilizing an expansion machine.
BACKGROUND ART
[0002] While a refrigeration cycle device utilizing a Freon family
refrigerant has been widely used as a multiple air conditioner for
office buildings, a super critical refrigeration cycle utilizing a
super critical fluid such as CO.sub.2 refrigerant is recently
suggested to be installed in a multiple air conditioner for office
buildings.
[0003] A super critical fluid is in a super critical state at the
high pressure side, and the low pressure side is also at a higher
pressure as compare to that of the Freon family refrigerant, so
that the refrigeration system using the super critical fluid is a
trans-critical cycle ranging over the critical point, providing a
condition different from the conventional refrigeration cycle.
Because of such the large difference between the high and low
pressure, the input value of the air conditioning system needs to
be large, and the super critical fluid generates a large
temperature difference, different from the fluid of the
vapor-liquid phase, so that, during the cooling operation when the
outdoor air temperature is high, the temperature difference
relative to the outdoor temperature is small, a sufficient heat
exchange cannot be being performed, leading to an insufficient
cooling, resulting in a COP inferior to that of the air conditioner
utilizing the conventional Freon refrigerant.
[0004] Therefore, in order to suppress the high pressure at the
compressor discharge portion and maintain the refrigerant ability
of the super critical fluid, an expansion machine is installed and
an intermediate cooler is utilized. An explanation will now be made
as to a conventional example in which a second heat source side
heat exchanger (second gas cooler) is used in the refrigeration
cycle utilizing the second compressor driven by an expansion power
recovered by an expansion machine. In the conventional example, an
intermediate cooling system has been adopted, in which the second
heat source side heat exchanger is disposed in a pipe between the
first compressor and the second compressor, and the high pressure
refrigerant compressed by the compressor is cooled by the second
heat source side heat exchanger before it is compressed by the
second compressor (see patent document 1, for example).
[0005] With such the construction, as compared to the compression
stroke without using the intermediate cooling by the second heat
source side heat exchanger, the intermediate two-stage compression
needs less work for the compression, providing a higher COP for the
same refrigeration capacity. Also, the COP during the heating
operation is less improved than that during the cooling operation,
so that the second heat source side heat exchanger is disposed in
the outdoor unit and arranged to be operated only during the
cooling operation in which a large improvement in efficiency can be
obtained.
[0006] [Patent Document 1] Japanese Patent Laid-Open No.
2003-279179 (claim 5, FIG. 14, etc.)
DISCLOSURE OF INVENTION
[0007] In the conventional example, the construction was such that
the second heat source side heat exchanger (second gas cooler) is
used in a flow path between the low pressure main compressor and
the high pressure sub compressor. When the second heat source side
heat exchanger is disposed in a flow path between the low pressure
main compressor and the high pressure sub compressor, the second
heat source heat exchanger has been bypassed during the cooling
operation, the heat transfer area of the evaporator is decreased,
disadvantageously degrading the efficiency of the refrigerant.
[0008] Also, since the heat transfer area ratio of the first heat
source side heat exchanger and the second heat source side heat
exchanger has not been optimized against the volume ratio of the
expansion machine volume and the second compressor volume, the
expansion machine was poor in the poor recovery efficiency,
disadvantageously degrading the efficiency. Also, the heat
dissipation amount of the second heat source side heat exchanger
has not been optimized in accordance with the environmental
conditions such as the outdoor temperature, indoor temperature, air
conditioner load and the like, so that the efficiency was not
high.
[0009] Also, since the relationship between the heat radiator
outlet temperature and the opening and closing operation of the
pre-expansion valve and the bypass valve has not been clear, those
valves could not properly be controlled, degrading the power
recovery efficiency at the expansion machine.
[0010] Also, since the air speed distribution in the heat exchanger
relative to the column direction has not been taken into
consideration, the heat exchanger had a air speed profile in the
direction of column of the heat exchanger in the actual use of the
first and the second heat source side heat exchangers, undesirably
decreasing the efficiency. Also, since the first and the second
heat source side heat exchangers were independently used, the
circuit structure was complex and the manufacturing cost was
increased.
[0011] The present invention was made to solve the above problems
of the conventional design and has as its object the provision of a
refrigeration cycle device that efficiently utilizes an expansion
machine, decreases the installation space for the heat exchanger
and that decreases the manufacturing cost of the unit.
[0012] In order to solve the above problems, the present invention
provides a refrigeration cycle device comprising a first
compressor, a second compressor driven by recovered power recovered
by an expansion machine, refrigerant flow path changeover means, a
load side heat exchanger, a first heat source side heat exchanger
and a second heat source side heat exchanger, and changeable
between a cooling operation and a heating operation by said
refrigerant flow path change-over means; wherein said second
compressor and said first compressor are connected in series; said
second heat source side heat exchanger is disposed between said
first compressor and said second compressor during the cooling
operation, and wherein the operation is performed by the
utilization of said first heat source side heat exchanger and said
second heat source side heat exchanger irrespective of operation
mode.
[0013] The present invention also provides a refrigeration cycle
device comprising a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, refrigerant flow
path changeover means, a load side heat exchanger, a first heat
source side heat exchanger and a second heat source side heat
exchanger, and changeable between a cooling operation and a heating
operation by said refrigerant flow path changeover means; wherein
said second compressor and said first compressor are connected in
series; said second heat source side heat exchanger is disposed
between said first compressor and said second compressor during the
cooling operation, and wherein heat transfer area ratio, which is a
ratio of the heat transfer area of the second heat source side heat
exchanger relative to the total heat transfer area of the heat
transfer areas of said first and second heat source side heat
exchangers provided on the high pressure side, is made 0.2-0.6.
[0014] The present invention also provides a refrigeration cycle
device, wherein an indoor unit self-containing a first compressor,
a second compressor driven by recovered power recovered by an
expansion machine, and a plurality of indoor units self-containing
a load side heat exchanger and an on-off valve are connected by a
pipe, and said plurality of indoor units are independently
changeable between a cooling operation and a heating operation;
wherein said second compressor and said first compressor are
connected in series; said second heat source side heat exchanger is
disposed between said first compressor and said second compressor
during the cooling operation, and wherein the operation is
performed by the utilization of said first heat source side heat
exchanger and said second heat source side heat exchanger
irrespective of the operation modes of said indoor units.
[0015] The present invention also provides a refrigeration cycle
device comprising a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, refrigerant flow
path changeover means, a load side heat exchanger, a first heat
source side heat exchanger and a second heat source side heat
exchanger; wherein said first compressor and said second compressor
are connected in series in a refrigerant flow path; said second
heat source side heat exchanger is disposed in a flow path between
said first compressor and said second compressor during the cooling
operation; said first heat source side heat exchanger and said
second heat source side heat exchanger during the cooling operation
are in an integral structure or in a divided structure so that fins
are not common in the direction of column; and wherein heat
transfer area ratio, which is a ratio of the heat transfer area of
the second heat source side heat exchanger relative to the total
heat transfer area of the heat transfer areas of said first and
second heat source side heat exchangers, is set, according to the
air speed distribution, with the air speed distributions of said
first and second heat source side heat exchanger taken into
consideration, within a range including a point at which the COP is
at a maximal.
[0016] The present invention also provides a refrigeration cycle
device comprising a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, refrigerant flow
path changeover means, a load side heat exchanger, a first heat
source side heat exchanger and a second heat source side heat
exchanger; wherein said first compressor and said second compressor
are connected in series in a refrigerant flow path; said second
heat source side heat exchanger is disposed in a flow path between
said first compressor and said second compressor during the cooling
operation; said first heat source side heat exchanger and said
second heat source side heat exchanger during the cooling operation
are in an integral structure or in a divided structure so that fins
are not common in the direction of column; and wherein a fan is
disposed higher than or beside of the heat exchanger and said
second heat source side heat exchanger is disposed down stream side
of said first heat source side heat exchangers.
[0017] The present invention also provides a refrigeration cycle
device comprising a first compressor, a second compressor driven by
recovered power recovered by an expansion machine, refrigerant flow
path changeover means, a load side heat exchanger, a first heat
source side heat exchanger and a second heat source side heat
exchanger; wherein said first compressor and said second compressor
are connected in series in a refrigerant flow path; said second
heat source side heat exchanger is disposed in a flow path between
said first compressor and said second compressor during the cooling
operation; said first heat source side heat exchanger and said
second heat source side heat exchanger during the cooling operation
are in an integral structure or in a divided structure so that fins
are not common in the direction of column; and wherein a fan is
disposed higher than or beside of the heat exchanger and said
second heat source side heat exchanger is disposed down stream side
of said first heat source side heat exchangers.
ADVANTAGEOUS RESULTS OF THE INVENTION
[0018] According to the present invention, the second heat source
side heat exchanger is utilized even during the heating operation,
so that the heat transfer area of the evaporator is increased as
compared to the conventional design, enabling to provide a
refrigeration cycle device of a high efficiency. Also, by
optimizing the heat transfer area ratio between the first heat
source side heat exchanger and the second heat source side heat
exchanger and the volume ratio of the expanding machine volume and
the second compressor volume, the efficiency of the refrigeration
cycle can be improved. Further, by modifying the heat radiation
amount of the first heat source side heat exchanger or the second
heat source side heat exchanger according to the environmental
conditions, a high efficiency of the refrigeration cycle can be
always maintained.
[0019] According to the present invention, by taking into
consideration the heat transfer area ratio of the first heat source
side heat exchanger and the second heat source side heat exchanger
and the volume ration of the expansion machine volume and the
second compressor volume as well as the air speed distribution,
when the actual air conditioner utilizes the first heat source side
heat exchanger and the second heat source side heat exchanger, the
concrete structure and the installation are determined, and a
refrigeration cycle device of a high efficiency can be provided.
Also, the second heat source side heat exchanger is utilized during
the heating operation, the heat transfer area of the evaporator is
increased as compared to the conventional example, enabling the
provision of a high efficiency refrigeration cycle device.
[0020] Also, when the first heat source side heat exchanger and the
second heat source side heat exchanger are actually put in use,
they can be manufactured and installed similarly to the
conventional heat exchanger, so that the circuit construction can
be simplified and the installation space for the first heat source
side heat exchanger and the second heat source side heat exchanger
can be simplified, so that the manufacturing cost can be
reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a view showing the construction of the
refrigeration cycle device of the present invention (Embodiment
1).
[0022] FIG. 2 is a view showing the cooling operation on the P-h
diagram of the refrigeration cycle device of the present invention
(Embodiment 1).
[0023] FIG. 3 is a view showing the heating operation on the P-h
diagram of the refrigeration cycle device of the present invention
(Embodiment 1).
[0024] FIG. 4 is a view showing the relationship of the ratio of
the volume of the second compressor and the COP improvement ratio
relative to the expansion machine volume of the refrigeration cycle
device of the present invention (Embodiment 1).
[0025] FIG. 5 is a view showing the relationship between the heat
transfer area ratio and the COP improvement ratio of the
refrigerant cycle device of the present invention (Embodiment
1).
[0026] FIG. 6 is a view showing the structure of the outdoor heat
exchanger of the refrigerant cycle device of the present invention
(Embodiment 1).
[0027] FIG. 7 is a view showing a section of the second compressor
integral type expansion machine of the of the refrigerant cycle
device of the present invention (Embodiment 1).
[0028] FIG. 8 is a view showing the operation on the P-h diagram of
the refrigerant cycle device of the present invention when the
outdoor temperature is changed (Embodiment 1).
[0029] FIG. 9 is a view showing the flow chart of the expansion
machine control method of the refrigeration cycle device of the
present invention (Embodiment 1).
[0030] FIG. 10 is a view showing the construction of the
refrigerant cycle device of the present invention (Embodiment
2).
[0031] FIG. 11 is a view showing the structure of the refrigeration
cycle device of the present invention (Embodiment 3).
[0032] FIG. 12 is a view showing a section of the second compressor
integral type expansion machine of the refrigeration cycle device
of the present invention (Embodiment 3).
[0033] FIG. 13 is a plan view showing the second compression
mechanism of the second compressor integral type expansion machine
of the refrigeration cycle device of the present invention
(Embodiment 3).
[0034] FIG. 14 is a sectional view showing the flows of the
refrigerant and the oil of the second compressor when there is no
bypass of the refrigeration cycle device of the present invention
(Embodiment 3).
[0035] FIG. 15 is one example of a sectional view showing the flows
of the refrigerant and the oil of the second compressor when there
is a bypass of the refrigeration cycle device of the present
invention (Embodiment 3).
[0036] FIG. 16 is another example of a sectional view showing the
flows of the refrigerant and the oil of the second compressor when
there is a bypass of the refrigeration cycle device of the present
invention (Embodiment 3).
[0037] FIG. 17 is a view showing the air speed distribution in the
column direction of the outdoor heat exchanger of the refrigeration
cycle device of the present invention (Embodiment 4).
[0038] FIG. 18 is a view showing the structure of the outdoor heat
exchanger when the second outdoor heat exchanger is disposed on the
upper stage in the refrigeration cycle device of the present
invention (Embodiment 4).
[0039] FIG. 19 is a view showing the relationship between the heat
transfer area ratio and the COP improvement ratio when the second
outdoor heat exchanger is disposed on the upper stage in the
refrigeration cycle device of the present invention (Embodiment
4).
[0040] FIG. 20 is a view showing the structure of the outdoor heat
exchanger when the second outdoor heat exchanger is disposed on the
lower stage of the refrigeration cycle device of the present
invention (Embodiment 5).
[0041] FIG. 21 is a view showing the relationship between the heat
transfer area ratio and the COP improvement ratio when the second
outdoor heat exchanger is disposed on the lower stage in the
refrigeration cycle device of the present invention (Embodiment
5).
[0042] FIG. 22 is a view showing the structure of the outdoor heat
exchanger when the second outdoor heat exchanger is disposed in a
row in the refrigeration cycle device of the present invention
(Embodiment 6).
[0043] FIG. 23 is a view showing the structure of the outdoor heat
exchanger when the second outdoor heat exchanger is disposed in a
straight line in the refrigeration cycle device of the present
invention (Embodiment 7).
BEST MODE FOR CARRYING OUT THE INVENTION
[0044] The description will now be made in terms of a refrigerant
cycle device according to embodiment 1 of the present
invention.
Embodiment 1
[0045] FIG. 1 is a schematic diagram showing a refrigerant cycle
device according to the embodiment 1 of the present invention. In
the figure, the refrigerant cycle device of this embodiment
comprises an outdoor unit 100 self-containing a first outdoor heat
exchanger 3a which is a first heat source side heat exchanger, a
second outdoor heat exchanger 3b which is a second heat source side
heat exchanger, indoor units 200a, 200b self-containing an indoor
heat exchangers 9a, 9b which are load side heat exchanger and a gas
pipe 51 and a liquid pipe 52 connecting the outdoor unit 100 and
the indoor units 200a, 200b. Filled within this refrigerant circuit
as a refrigerant is for example carbon dioxide which becomes the
critical state at a critical temperature (about 31 degree
Celsius).
[0046] The indoor unit 100 comprises a first compressor 1 for
compressing a refrigerant gas, a four-way valve 2 and a four-way
valve 4 which are refrigerant flow path change-over means for
changing the direction of flow of the refrigerant in accordance
with the operation mode of the indoor units 200a and 200b, a first
outdoor heat exchanger 3a and a second outdoor heat exchanger 3b
which serves as a heat radiator or an evaporator in accordance with
the operation mode, an expansion machine unit 5 in which an
expansion machine 5a and the second compressor 5b are integrally
constructed, and an unillustrated blower for supplying outdoor air
to the outer surface of the first outdoor heat exchanger 3a and the
second outdoor heat exchanger 3b, the entire unit being installed
outdoor. Also, the first outdoor heat exchanger 3a is disposed
between the four-way valve 2 and the four-way valve 4, and the
second outdoor heat exchanger 3b is disposed between the first
compressor 1 and the second compressor 5b during the cooling
operation. Disposed within the expansion machine unit 5 are the
expansion machine 5a and the second compressor 5b, which are
connected together by a common shaft. In the expansion machine unit
5, the expansion machine 5 and the second compressor 5a for example
are both composed of the scroll type expansion machine and the
compressor, the loads in the thrust direction in the expansion
machine and the compressor are cancelled out at both surfaces. The
second compressor 5b has formed therein a bypass circuit, the
bypass circuit having a bypass valve 53 therein. In order to
equalize the passing refrigerant flow rate and the power at the
expansion machine 5a and the second compressor 5b, the expansion
machine 5a has, at the inlet side thereof, an on-off valve 6
(hereinafter referred to as a pre-expansion valve 6) connected in
series and an on-off valve 7 (hereinafter referred to as a bypass
valve 7) connected in parallel. Also, the first outdoor heat
exchanger 3a and the second outdoor heat exchanger 3b are connected
via check valves 54 and 55 as on-off valve, the check valves 54 and
55 are set at a minimum operation pressure difference (0.5 MPa, for
example). Also, electromagnetic valves 57 and 58 which are on-off
valves are disposed at the inlet portion of the outdoor heat
exchanger 3b.
[0047] The indoor units 200a and 200b comprises indoor heat
exchangers 9a and 9b which are load side heat exchangers,
electronic expansion valves 8a and 8b which are depressurizing
means capable of changing the opening degree for regulating the
refrigerant distribution to the indoor heat exchangers 9a and 9b,
and unillustrated blower and piping for supplying a forced indoor
air flow onto the outer surface of the indoor heat exchangers 9a
and 9b. The indoor heat exchangers 9a and 9b are connected at their
one ends to the gas pipe 51 and at the other ends to the liquid
pipe 52 via the electronic expansion valves 8a and 8b. It is to be
noted that, while two indoor units 200a and 200b are shown in this
embodiment, they may be one or more than three. Also, the
electronic expansion valves 8a and 8b which are the depressurizing
means having a variable degree of opening for adjusting the
refrigerant distribution to the indoor heat exchangers 9a and 9b
may not be used and an expansion machine may be used as the
depressurizing mans instead.
[0048] Also, to obtain target values for the balance control of the
passing refrigerant flow rate and the power at the expansion
machine unit 5, a discharge temperature detector 11 of the second
compressor 5b, an outlet temperature detector 12 of the first
outdoor heat exchanger 3a, an outdoor air temperature detector 13,
and an indoor temperature detector 14 are provided. The data from
them are supplied to an unillustrated controller to perform the
necessary operation therein and commands of the degree of opening
are transmitted to the pre-expansion valve 6 and the bypass valve 7
which are actuators.
[0049] The operation of the refrigerant cycle device having the
structure as described above will now be described. It is to be
noted that the operation which will be explained bellow is
performed by the controller 300. First, the operation for cooling
will be explained on the basis of FIGS. 1 and 2. FIG. 2 is a graph
showing the sates of the refrigerant at points A-H in the
refrigerant circuit shown in FIG. 1 are plotted on the P-h diagram.
During the cooling operation, the four-way valve 2 in the outdoor
unit 100 is set so that the first port 2a and the second port 2b
are in communication with each other and the third port 2c and the
fourth port 2d are in communication with each other, and the
four-way valve 4 is set so that the first port 4a and the fourth
port 4d are in communication with each other and the second port 4b
and the third port 4c are in communication with each other (solid
line in FIG. 1). Also, the pre-expansion valve 6 and the bypass
valve 7 are set at a suitable initial degree of opening depending
upon the outdoor air temperature, the room temperature and the
load, and the electronic expansion valves 8a and 8b are fully
opened. The electromagnetic valve 56 is closed and the
electromagnetic valves 57 and 58 are opened. While the necessary
depressurizing function is achieved by the expansion machine 5a,
when a proper superheating (such as 1-10 degree Celsius) cannot be
obtained at both outlet portions of the indoor heat exchangers 9a
and 9b, the pre-expansion valve 6 is adjusted into the closing
direction to obtain the necessary depressurization.
[0050] At this time, the high temperature and high pressure gas
refrigerant (state A) discharged from the first compressor 1 passes
through the electromagnetic valve 57 because of the closed
electromagnetic valve 56, cooled by a certain amount at the second
outdoor heat exchanger 3b (state B), and flows into the second
compressor 5b. At this time the check valves 54 and 55 disposed at
the outlet and inlet ports of the second outdoor heat exchanger 3b
is closed due to the pressure difference. The refrigerant that
passed the electromagnetic valve 58 and flowed into the second
compressor 5b driven by the expansion machine 5a, is compressed by
an amount corresponding to the power recovered at the expansion
machine. At this time, the bypass valve 53 disposed in relation to
the second compressor 5b, which is in the open state during the
starting period in which no pressure difference is generated, is
closed due to the pressure difference across the second compressor
5b when the second compressor 5b is driven by the expansion machine
5a. The refrigerant discharged from the second compressor 5b flows
through the first port 2a, the second port 2b (state C), dissipates
heat into the air or the medium to be heated in the first outdoor
heat exchanger 3a (state D), and flows into the pre-expansion valve
6 through the second port 4a and the third port 4c of the four-way
valve 4. The refrigerant (state E) regulated by the pre-expansion
valve 6 as to the density at the inlet of the expansion machine 5a
is depressurized at the expansion machine 5a and flows through the
first port 4a and the fourth port 4d of the four-way valve 4 to
pass through the liquid pipe 52 (state F). At this time, the bypass
valve 7 of the expansion machine 5a is controlled so that the
refrigerant flow rate through the second compressor 5b and the
recovered power is in balance. Then, the refrigerant is slightly
depressurized (state G) at the electronic expansion valves 8a and
8b which are depressurizing means in the indoor unit 200a and 200b,
flows into the gas pipe 51 after the thermal load in the space to
be air conditioned is treated by the indoor heat exchangers 9a and
9b, and then flows from the fourth port 2d through the third port
2c of the four-way valve 2 into the first compressor 1 (state H).
At this time, when only one of the outlet portions out of the
indoor heat exchanger 9a and the indoor heat exchanger 9b does not
become the set superheating temperature (1-10 degrees Celsius), the
depressurizing means 8a and 8b are adjusted so that the degrees of
the outlet superheat of the inner heat exchangers 9a and 9b are
equal.
[0051] The description will be made as to the heating operation on
the basis of FIGS. 1 and 3. In this embodiment, while an example in
which the expansion machine is used even in the heating operation
will be described, since the density ratio at the inlet portion of
the expansion machine 5a and the inlet portion of the second
compressor 5b is large during the heating operation, the expansion
power recovery loss for balancing the passing refrigerant flow rate
and the recovery power. Therefore, the arrangement may be such that
the four-way valve 4 is eliminated according to the necessity and
that the expansion machine unit 5 is not used during the heating
operation.
[0052] During the heating operation of this embodiment, the
four-way valve 2 in the outdoor unit 100 is set so that the first
port 2a and the fourth port 2d are in communication with each other
and the second port 2b and the third port 2c are in communication
with each other, and the four-way valve 4 is set so that the first
port 4a and the second port 4b are in communication with each other
and the third port 4c and the fourth port 4d are in communication
with each other. In this case, the electronic expansion valves 8a
and 8b in the indoor units 200a and 200b are fully opened, and the
basic depressurizing function is achieved by the expansion machine
5 and when the amount of depressurization is insufficient, the
pre-expansion valve 6 is adjusted to obtain the necessary
depressurization so that a proper temperature dependent upon the
room temperature is obtained at the outlet portions of the indoor
heat exchangers 9a and 9b.
[0053] At this time, the high temperature and high pressure gas
refrigerant (state A) discharged from the first compressor 1 passes
through the electromagnetic valve 56 because of the closed
electromagnetic valves 57 and 58, flows from the first port 2a,
through the fourth port 2d and the gas pipe 51 and flows into the
indoor units 200a and 200b after further compressed by the second
compressor 5b (state B). The high temperature and high pressure
refrigerant flowed into the indoor units 200a and 200b flows into
the indoor heat exchangers 9a and 9b to radiate heat into the air
in the room to heat the room and to lower its temperature (state
G). This refrigerant at the medium temperature and high pressure
flows through the electronic expansion valves 8a and 8b (state F)
and flows into the liquid pipe 52. The refrigerant flowed into the
liquid pipe 52 passes through the fourth port 4d and the third port
4c of the four-way valve 4 and flows into the pre-expansion valve
6. The refrigerant flowing out from the pre-expansion valve 6
(state E) flows into the expansion machine 5a, through the first
port 4a and the second port 4b of the four-way valve 4 and flows
into the first and the second outdoor heat exchangers 3a and 3b. At
this time, the check valves 54 and 55 are brought into the open
state because the pressure difference (such as 0.5 MPa) necessary
for valve closing cannot be obtained. Then, the gas refrigerant
(state C) evaporated in the first and the second outdoor heat
exchangers 3a and 3b is returned to the suction portion (state H)
of the first compressor 1 via the second port 2b and the third port
2c of the four-way valve 2.
[0054] The heat transfer area ratio of the second outdoor heat
exchanger 3b relative to the total heat transfer area of the
outdoor heat exchanger when the air speed flowing into the outdoor
heat exchanger is constant will now be described. FIG. 4 is a graph
in which the ratio of the volume of the second compressor 5b
relative to the volume of the expansion machine 5a (hereinafter
referred to expansion compression volume ratio) is plotted against
the axis of ordinate and the COP improvement ratio is plotted
against the axis of abscissa, with the above mentioned heat
transfer area is used as the parameter. The heat transfer area here
means the ratio of the heat transfer area of the second outdoor
heat exchanger 3b relative to the total heat transfer area of the
outdoor heat exchangers, i.e., the first outdoor heat exchanger 3a
and the second outdoor heat exchanger 3b. The COP improvement ratio
shown on the axis of ordinate is a value for the refrigerant
circuit in which the heat transfer area of the second outdoor heat
exchanger 3b is 0.1 and an expansion machine 5a is not provided. A
general tendency of the COP improvement ratio indicates it has a
local maximal at about the expansion compression volume ratio of 2.
For example, at the heat transfer area ratio of 0.4 (symbol
.quadrature.), it has a local maximal at about the expansion
compression volume ratio of 2.1. This is because, when the
expansion compression volume ratio is larger than 2.1, the second
compressor volume is large and the number of rotation is decreased,
so that a pre-expansion loss for increasing the rotational number
is generated, and when the expansion compression volume ratio is
less than 2.1, the second compressor volume is small and the number
of rotation is increased, so that a bypass loss for decreasing the
rotational number is generated. For the heat transfer area ratio of
0.2, the local maximal of the COP ratio, at the expansion
compression volume ratio of 2.4 where the COP is at it local
maximal, is lower than that where the heat transfer area is 0.4 by
4% (from 1.225 to 1.185). Therefore, it is understood that there is
an expansion compression volume ratio that causes the COP
improvement ratio to become the local maximal, and its value is
within the range of 1.8-2.3 as shown by white arrow in FIG. 4.
[0055] FIG. 5 is graph showing the COP improvement ratio relative
to the heat transfer area ratio of the second outdoor heat
exchanger 3b when the air flow rate distribution is uniform
relative to the column direction of the heat exchanger, the
expansion compression volume ratio is at the optimum value shown in
FIG. 4. In FIG. 5, a shows the COP improvement ratio when an
expansion machine is installed, b shows the COP improvement ratio
when no expansion machine is installed, and c shows the discharge
pressure change of the first compressor 1 when an expansion machine
is installed. When the heat transfer area ratio of the second
outdoor heat exchanger 3b is increased, the heat exchange amount at
the second heat exchanger 3b is increased, thereby the discharge
pressure of the first compressor 1 (the suction pressure at the
second compressor 5b), and the input of the first compressor 1 is
decreased (the COP improvement ratio is increased). However, when
the heat transfer area of the second outdoor heat exchanger 3b is
increased too much, the heat exchange amount that should be handled
at the second outdoor heat exchanger 3b increases, whereby the
discharge pressure of the first compressor 1 turns into increase
and the input is increased. Therefore, it is understood that there
is an optimum value of the heat transfer area ratio of the second
outdoor heat exchanger 3b that makes the COP improvement ratio
local maximal, the value is within the range of from 0.3-0.5 as
shown in white arrow in FIG. 5, and that the advantageous effect is
significantly decreased at less than 0.3. It is understood from the
above, that the second outdoor heat exchanger 3b is arranged to
have a heat transfer area ratio of 0.3-0.5 and an expansion
compression volume ratio of 1.8-2.3, the performance of the
expansion machine installed circuit can be fully utilized.
[0056] As for the heat transfer area ratio, the range of 0.3-0.5 is
the most preferable and the range of 0.2-0.6 is preferable, but the
COP improvement ratio is not sufficiently high when the heat
transfer area ratio is less than 0.2 and the heat transfer area
ratio larger than 0.6 is not practical. As for the expansion volume
ratio, the range of 1.8-2.3 is the most preferable and the range of
1.5-2.5 is preferable, but the COP improvement ratio is not
sufficiently high irrespective of the heat transfer area ratio when
its is less than 1.5 and the COP improvement ratio does not become
high even if it is larger than 2.5.
[0057] While FIG. 1 illustrates an example in which the first
outdoor heat exchanger 3a and the second outdoor heat exchanger 3b
is separated, this is not limiting, but the arrangement may be such
that, as shown in FIG. 6, the first outdoor heat exchanger 3a in
section A in the upper stage is utilized as an intermediate cooler,
and the second outdoor heat exchanger 3b in section B in the lower
stage is utilized as the main heat radiator, and that the ratio of
the section A to the section B is 4:6. Also, as shown in FIG. 1,
the arrangement may also such that the outdoor heat exchanger is
divided in the row direction, the air shown by the while arrow
flows from right to left, so that the air first comes in contact
with the second outdoor heat exchanger 3b and then the air comes in
contact with the first outdoor heat exchanger 3a. Further, these
first and the second outdoor heat exchangers may be arranged into
an integral structure.
[0058] Also, in this embodiment, the arrangement is such that the
ratio of the heat transfer area of the second outdoor heat
exchanger relative to the total heat transfer area of the outdoor
heat exchangers is determined by only the performance during the
cooling operation. The above-mentioned heat transfer area ratio can
be determined only upon the performance during the cooling
operation because, when the outdoor heat exchanger is utilized as
an evaporator during the heating operation, the enthalpy difference
between the suction air and the refrigerant temperature
corresponding saturated moisturized air (in the evaporator, the
heat exchanger is in the moisturized state, so that the driving
temperature difference in the heat exchanging is the enthalpy
difference) is small, so that the effect of the heat transfer area
ratio on the performance is small.
[0059] The detailed structure of the expansion machine unit 5 is
shown in FIG. 7. FIG. 7 shows the expansion machine unit in which
the expansion machine 5a and the second compressor 5b are both of
the scroll structure, the expansion machine 5a is composed of an
expansion machine stationary scroll 351 and an expansion machine
orbiting scroll 362, and the second compressor 5b is composed of a
second compressor stationary scroll 361 and a second compressor
orbiting scroll 362. These scrolls have penetrated therein at the
central portion a shaft 308, and the shaft 308 is provided at its
both ends with balance weights 309a and 309b, and the shaft 308 is
supported by an expansion machine side bearing portion 351b and the
second compressor side bearing portion 361b. Also, the expansion
machine side scroll 352 of the orbiting scroll and the second
compressor mechanism side scroll 362 have a back-to-back structure
or have a base plate in common to provide an integral structure.
Also, a crank portion 308b for eccentrically drive the orbiting
scroll and an Oldham ring 307 for regulating the position are
provided all within a hermetic vessel 310.
[0060] In the expansion machine unit 5 having the above-described
structure, when the motion space for the orbiting scroll is made at
the low pressure atmosphere after expansion, an urging force is
generated from the second compressor 5b to the expansion machine
side. At this time, when the expansion compression volume ratio is
designed to be high (equal to or more than 2.3, for example), a
thrust load from the side of the second compressor 5a becomes large
with the same tooth height, so that the thrust load from the side
of the expansion machine 5a becomes excessively small with respect
to the thrust load from the second compressor 5b, the thrust load
from both sides cannot be offset, resulting in a difficult
structure of the expansion machine unit 5 in which the second
compressor 5b and the expansion machine 5a are integrally combined.
Also, the scroll at the side of the second compressor 5b may have
an extremely high tooth in order to reduce the thrust load on the
side of the second compressor 5b, but a problem of strength
generates in this case. Therefore, in an expansion machine unit
having the expansion machine 5a, the second compressor 5b as well
as the scroll structure, the expansion compression volume ratio is
set equal to or less than 2.3, whereby a reliable expansion unit
that cope with not only the balance between the passing refrigerant
flow rate and the power but also the balance between the thrust
loads.
[0061] The description will now be made as to the control method of
the expansion machine 5a. In this embodiment, pre-expansion valve
disposed in series with the expansion machine 5a at the inlet
portion of the expansion machine 5a and the bypass valve 7 provided
for bypassing the expansion machine 5a are used to control the
expansion machine 5a so that the flow rate passing through the
expansion machine 5a and the recovered power as well as the flow
rate passing through the second compressor 5b and the recovered
power are equal to each other. This control method will be
explained in conjunction with FIG. 8. FIG. 8 is a P-h diagram
showing the change in the operational state when the outdoor
temperature is changed under the conditions that the cooling load
is constant and the indoor temperature is constant. In the figure,
curves with fixed density .rho. and the curves with the fixed
temperature T are shown, and an equal density ratio line along
which the ratio of the expansion machine inlet density relative to
the second compressor inlet density is equal to 2 is shown in
broken line. Separated by this equal density ratio line as a
boundary, the upper right region of this line shows a bypass region
in which the density ratio of the expansion/compression is low
(expansion machine density is low), and the lower left region of
this line shows a pre-expansion region in which the density ratio
of the expansion/compression is high (expansion machine density is
high).
[0062] For example, suppose that the present operation state of the
refrigerant cycle is as at a in FIG. 8, then the operation state of
the refrigeration cycle is changed into b when the outdoor
temperature increased. At this time, as the outdoor temperature
increases, the heat radiator outlet temperature increases and the
inlet density of the expansion machine 5a decreases (the ratio of
the inlet density of the expansion machine 5a relative to the
suction density of the second compressor 5b is decreased).
Therefore, when the pre-expansion valve 6 is not in the fully open
state, the pre-expansion valve 6 is opened to increase the inlet
pressure and to increase the inlet density of the expansion machine
5a, thereby to decrease the rotational number of the expansion
machine 5a. When the pre-expansion valve 6 is fully opened, the
bypass valve 7 is opened to decrease the refrigerant flow rate
flowing through the expansion machine 5a and to similarly decrease
the rotational number. At this time, since the rotational number of
the second compressor 5b coaxially connected to the expansion
machine 5a is also decreased, the inlet pressure of the second
compressor 5b is increased to satisfy the condition of a constant
refrigerant flow rate. Also, when the pre-expansion valve 6 of the
expansion machine 5a is opened, the recovered power increases, so
that the suction pressure and the discharge pressure of the second
compressor 5b are both increased. While the recovered power of the
expansion machine 5a decreases when the bypass valve is opened,
comparing the amount of increase of the suction pressure of the
second compressor 5b and the amount of decrease of the discharge
pressure due to the decrease in the recovered power, the amount of
increase of the suction pressure of the second compressor 5b is
greater due to the refrigerant property, thus resulting in the
increase in the discharge pressure. In the manner described above,
the rotational number is decreased, thus balancing the refrigerant
flow rate flowing through the expansion machine 5a and the second
compressor 5b and the recovery power, regulating the outlet
temperature of the first outdoor heat exchanger 3a to a
predetermined value.
[0063] On the other hand, it is now assumed that the present
operational state of the refrigeration cycle is as shown by b in
FIG. 8, for example, the operational state of the refrigeration
cycle changes into c. At this time, the heat radiator outlet
temperature decreases as the outdoor temperature decreases and the
expansion machine inlet density increases (the ratio of the suction
density of the expansion machine 5a relative to the inlet density
of the second compressor 5b increases). Therefore, when the bypass
valve 7 is not in the fully closed state, the bypass valve 7 is
closed to increase the flow rate flowing through the expansion
machine 5a to increase the rotational number of the expansion
machine 5a. When the bypass valve 7 is fully closed, pre-expansion
valve 6 is closed to decrease the inlet pressure to decrease the
inlet density of the expansion machine 5a and to similarly increase
the rotational number. At this time, since the rotational number of
the second compressor 5b coaxially connected to the expansion
machine 5a is also increased, the suction pressure of the second
compressor 5b is decreased to satisfy the condition of a constant
refrigerant flow rate. Also, when the pre-expansion valve 6 of the
expansion machine 5a is closed, the suction pressure and the
discharge pressure are both decreased because the recovered power
decreases. While the recovered power of the expansion machine 5a
decreases when the bypass valve of the expansion machine 5a is
closed, comparing the amount of decrease of the suction pressure of
the second compressor 5b and the amount of increase of the
discharge pressure due to the increase in the recovered power, the
amount of decrease of the suction pressure of the second compressor
5b is greater due to the refrigerant property, thus resulting in
the decrease in the discharge pressure. In the manner as described
above, the rotational number is decreased, thus balancing the
refrigerant flow rate flowing through the expansion machine 5a and
the second compressor 5b and the recovery power, regulating the
outlet temperature of the first outdoor heat exchanger 3a to a
predetermined value.
[0064] When the outdoor temperature is extremely low, the power
recovery effect (the compression power for the second compressor
5b) is small as shown at d in FIG. 8, the necessary pressure
decrease may be obtained by the bypass valve 7 alone with the
pre-expansion valve 6 fully closed.
[0065] As above described, when the outdoor temperature is
increased, the bypass region for decreasing the rotation number of
the expansion machine 5a is provided, and when the outdoor
temperature is decreased, the pre-expansion region for increasing
the rotational number of the expansion machine 5a is provided.
Generalizing this, the equal density ratio line shown in the broken
line in FIG. 8 is being used as the boundary, when the ratio of the
inlet density of the expansion machine relative to the suction
density of the second compressor 5b high, the operation is
performed in the bypass region as shown by the white arrow pointing
in the upper right direction, and when the above density ratio is
low, the operation is performed in the pre-expansion region as
shown by the white arrow pointing in the left low direction. This
operation is similarly achieved also when the indoor temperature
and the air conditioning load is changed.
[0066] A concrete control algorism will now be described in
conjunction with FIGS. 1 and 9. As shown in FIG. 9, the indoor
temperature (Ti), the outdoor temperature (To) and the air
conditioner load (Q) are detected at ST1, and basing on these
values the inlet target temperature Tco m of the pre-expansion
valve 6 is calculated at ST2. The air conditioner load Q can be
assumed on the basis of the indoor temperature, the outdoor
temperature, the compressor frequency and the like. At ST3, the
inlet temperature Tco of the pre-expansion valve 6 is detected and
when the difference between the inlet temperature Tco and the inlet
target temperature Tco m is greater than .epsilon. 1 (.epsilon. 1
is a positive value) (ST4), the expansion machine deceleration mode
is carried out (ST5). In this case, if the pre-expansion valve 6 is
not fully opened (ST6), the pre-expansion valve 6 is opened (ST7),
and if the pre-expansion valve 6 is fully opened (ST6), the bypass
valve 7 is opened (ST7).
[0067] On the other hand, when the difference between the inlet
temperature Tco and the inlet target temperature Tco m is smaller
than -.epsilon. 1 (.epsilon. 1 is a positive value) (ST4), the
expansion machine acceleration mode is carried out (ST5). In this
case, if the bypass valve 7 is not fully closed (ST6), the bypass
valve 7 is closed (ST7), and if the bypass valve 7 is fully closed
(ST6), the pre-expansion valve 6 is closed (ST7).
[0068] Thus, the rotational number of the expansion machine unit 5
is increased or decreased to make the inlet temperature of the
pre-expansion valve 6 equal to the inlet target value Tco m. At
this time, when the absolute value of the difference between the
inlet temperature Tco and the inlet target temperature Tco m become
less than .epsilon. 1, the control is completed. While an example
is explained in which the inlet temperature Tco of the
pre-expansion valve 6 is controlled to the inlet target value, this
is not limiting but the discharge temperature Td of the first
compressor 1 or the second compressor 5b is detected and the
control may be carried out so that the Td is used as the target
value or the difference .DELTA. Tc between Td and Tco is used as
the target value. Also, the pressure sensor may be disposed at the
discharge portion of the first compressor 1 or the second
compressor 5b and the control may be carried out so that the
detected pressure is made equal to the target value.
[0069] While in this embodiment, the four-way valve 4 is used to
utilize the expansion machine for both the cooling operation and
the heating operation, the arrangement may be such that the
expansion machine 5a is used only during the cooling operation. In
this case, the second port 4b and the third port 4c as well as the
first port 4a and the fourth port 4d of the four-way valve 4 are
respectively connected so that the four-way valve 4 is not
necessary. At this time, a refrigeration circuit for recovering the
power using the expansion machine 5a is constituted during the
cooling operation, and a refrigeration circuit for not recovering
the power using the bypass valve of the expansion machine 5a during
the heating operation.
[0070] Also, while the expansion machine 5a in this embodiment has
the structure as shown in FIG. 7, this is not limiting, but the
arrangement may be such that a pressure relief valve disposed in a
pipe for bypassing the expansion mechanism inlet and outlet port
portion inside the expansion machine 5a is relieved when the
pressure difference across the expansion machine 5a is equal to or
greater than a predetermined value. In this case, when the pressure
difference is equal to or more than the predetermined value, the
relief valve is opened, so that an amount of passing refrigerant
flow corresponding to the pressure difference bypasses the
expansion element, making an electronic expansion valve disposed
externally of the expansion machine 5a is not necessary.
[0071] From the above, it is understood that a refrigeration cycle
device is obtained in which the second compressor 5b and the first
compressor 1 are connected in series, the second heat source side
heat exchanger 3b is disposed between the first compressor 1 and
the second compressor 5b, and in which the operation is carried out
utilizing the first heat source side heat exchanger 1 and the
second heat source side heat exchanger 5b irrespective of the
operational mode.
[0072] By arranging the heat transfer area ratio of the second
outdoor heat exchanger relative to the total heat transfer area of
the outdoor heat exchanger to be 0.3-0.5, and the ratio of the
expansion machine volume and the volume of the second compressor 5b
driven by the expansion machine (the expansion compression volume
ratio) to be 1.8-2.3, the refrigeration machine can be provided in
which the expansion machine can be effectively utilized and a high
performance is exhibited. Particularly, when the expansion machine
and the second compressor both have the scroll type structure and
when the expansion compression volume ratio is high, a structural
difficulty arises that the tooth height of the second compressor
side scroll becomes extremely high in order to decrease the thrust
load on the second compressor side, so that limiting the expansion
compression volume ratio to less than 2.3 is effective to improve
the reliability. Also, by detecting the inlet temperature of the
pre-expansion valve and the discharge temperature of the second
compressor driven by the expansion machine, and controlling the
degrees of opening of the pre-expansion valve and the bypass valve
on the basis of these detected values, the passing refrigerant flow
rate flowing through the expansion machine and the recovered power
can be regulated to efficiently utilize the expansion machine.
Embodiment 2
[0073] The refrigeration cycle device according to the second
embodiment of the present invention will now be described. FIG. 10
is schematic diagram showing the refrigeration cycle device
according the second embodiment of the present invention, which is
different from the first embodiment is that the cooling operation
and the heating operation can be selected for each of the indoor
units and that the outdoor heat exchanger is divided into three
sections. In FIG. 10, the refrigerant cycle device according to
this embodiment comprises the outdoor unit 100 including therein
the first outdoor heat exchanger 3a, the second outdoor heat
exchanger 3b and the third outdoor heat exchanger 3c, the indoor
units 200a, 200b and 200c including the indoor heat exchangers 9a,
9b and 9c, the shunt unit 300 for controlling the shunted state of
the refrigerant, and a high pressure pipe 63 and a low pressure
pipe 64 connecting the outdoor unit 100 and the shunt unit 300.
This cycle contains carbon dioxide which becomes the supercritical
state at a critical temperature (about 31 degree Celsius) as the
refrigerant.
[0074] The outdoor unit 100 disposed outdoor comprises the first
compressor 1 for compressing the refrigerant gas, a four-way valve
2 or a first refrigerant flow path change over means for changing
the flow direction of the refrigerant according to the operational
mode, the first outdoor heat exchanger 3a, the second outdoor heat
exchanger 3b and the third outdoor heat exchanger 3c serving as a
condenser or an evaporator according to the operational mode, the
expansion machine unit 5 in which the expansion machine 5a and the
second compressor 5b are integrally combined, and an unillustrated
blower for forcedly supplying an air flow to the outer surface of
the outdoor heat exchangers 3a, 3b and 3c. The expansion machine
unit 5 has disposed therein the expansion machine 5a and the second
compressor 5b, which are coaxially connected together. The second
compressor 5b has disposed therein a bypass circuit, which has a
bypass valve 53 or a check valve disposed therein as an-on off
valve. In order to balance the flow rate and the power of the
expansion machine 5a and the second compressor 5b, the expansion
machine 5a is provided with, in series, the on-off valve 6
(hereinafter referred to also as pre-expansion valve) which is an
electronic expansion valve which is an on-off means capable of
changing the degree of opening, and with, in parallel, the on-off
valve 7 (hereinafter referred to also as the bypass valve) which is
an electronic expansion valve. Also, in order to flow the
refrigerant in the high pressure pipe 63 and the low pressure pipe
64 in the same direction, check valves 90, 91 and 92 for example
are disposed as on-off valves, and in order to change over between
the cooling operation and the heating operation, a check valve 94
and an electromagnetic valve 29 are disposed as on-off valves.
Also, in order to control the flow of the refrigerant into the
first outdoor heat exchanger 3a, the second outdoor heat exchanger
3b and the third outdoor heat exchanger 3c, the electromagnetic
valves 26, 27 and 28 are disposed as on-off valves, and the check
valves 93, 96 and 97 are disposed for preventing counter flow
during the cooling operation.
[0075] The shunt unit 300 contains therein the electronic expansion
valves 20 and 21 which are depressurizing device and the
electromagnetic valves 30-35 which are on-off valves.
[0076] The indoor units 200a, 200b and 200c respectively comprises
the indoor heat exchangers 9a, 9b and 9c, the electronic expansion
valves 8a, 8b and 8c which are depressurization means capable of
changing the degree of opening for adjusting the refrigerant
distribution to each indoor heat exchanger, unillustrated blowers
for forcedly supplying the indoor air to the outer surfaces of the
respective indoor heat exchangers, and the piping for connecting
the above elements. The indoor heat exchangers 9a, 9b and 9c each
has one end directly connected to the shunt unit 300, and the other
end connected to the shunt unit 300 via the electronic expansion
valves 8a, 8b and 8c. While there are three indoor units are
provided in this embodiment, two or more than four units may
equally be provided.
[0077] The operation of the refrigeration cycle device as above
construction will now be described. The refrigerant cycle device in
this embodiment has four operation modes of the full cooling
operation, the full heating operation, the cooling dominant
operation and the heating dominant operation. First the full
cooling operation in which the expansion machine unit 5 is utilized
to recover power will be described in conjunction with FIG. 10. In
the full cooling operation, the four-way valve 2 in the outdoor
unit 100 is set so that the first port 2a and the fourth port 2d
communicate with each other and the third port 2c and the second
port 2b communicate with each other (solid line in FIG. 10). The
electronic expansion valves 8a, 8b and 8c in the indoor units are
fully closed. The electronic expansion valve 20 is fully opened and
21 is fully closed. The necessary depressurizing function is
realized by the expansion machine 5a, but when a proper super
heating (5-10.degree. C., for example) cannot be obtained at the
outlet portions of any of the indoor heat exchangers 9a, 9b and 9c,
the pre-expansion valve 6 is adjusted in the closing direction to
obtain the necessary depressurization.
[0078] In the full cooling operation, the heat radiation amount of
the respective discharged refrigerant from the first compressor 1
and the second compressor 5b can be adjusted by opening and closing
of the electromagnetic valves 26, 27 and 28 in the indoor unit 100,
the description in this embodiment will be made as to where the
electromagnetic valves 27 and 28 are opened and the electromagnetic
valve 26 is closed. The electromagnetic valve 29 is closed. The
electronic expansion valve 20 in the shunt unit 300 is fully
opened, the valve 21 is fully closed, the electromagnetic valves
30, 32 and 34 are set in the open state, and the electromagnetic
valves 31, 33 and 35 are set in the closed state. At this time, the
high temperature, high pressure gas refrigerant discharged from the
first compressor 1 flows from the third port 2c of the four-way
valve 2 via the second port 2b and into the check valve 94 because
the electromagnetic valve 29 is closed. The refrigerant that passes
through the check valve 94 flows through the electromagnetic valves
27 and 28 because the check valve 97 is closed due to the pressure
difference by the second compressor 5b, flows through the second
outdoor heat exchanger 3b and the third outdoor heat exchanger 3c
in parallel to radiate heat therein, and the flow joins at the heat
exchanger outlet portion. The joined refrigerant flows into the
second compressor 5b driven by the recovered power of the expansion
machine 5a because the check valve 96 is closed due to the pressure
difference at the second compressor. The refrigerant flowed into
the second compressor 5b is compressed by an amount corresponding
to the power recovered by the expansion machine 5a.
[0079] The bypass valve 53 disposed in the second compressor 5b is
opened during the start up when there is no pressure difference,
but is closed due to the pressure difference when the second
compressor 5b is driven by the power recovered by the expansion
machine 5a.
[0080] The refrigerant discharged form the second compressor 5b
passes through the check valve 93, radiates heat to the air which
is the medium to be heated by the first outdoor heat exchanger 3a,
distributed to the pre-expansion valve 6 and the bypass valve 7 due
to the closed electromagnetic valve 29. The refrigerant regulated
by the pre-expansion valve 6 in terms of the inlet density at the
expansion machine 5a is depressurized by the expansion machine 5a
and joined to the refrigerant depressurized by the bypass valve 7,
and passes through the high pressure pipe 63 because the check
valve 92 is closed. At this time, the bypass valve 7 of the
expansion machine 5a is controlled so that the refrigerant flow
rate passing through the second compressor 5b and the recovered
power are balanced with each other. Thereafter, the refrigerant
flows into the shunt unit 300, passes through the electronic
expansion valve 20 and the distribution flow rate ratio to each
heat exchangers is adjusted by the electronic expansion valves 8a,
8b and 8c in the indoor units 200a, 200b and 200c, and after
processing the thermal load in the space to be air-conditioned by
the indoor heat exchangers 9a, 9b and 9c, flows into the low
pressure pipe 64 via the electromagnetic valves 30, 32 and 34, and
flows into the first compressor 1 through the fourth port 4d and
the first port 4a of the four-way valve 2. As has been described,
in this embodiment, during the full cooling operation, the power
recovery is achieved by the expansion machine 5a and the operation
is carried out in the two-stage compression cycle utilizing the
second compressor 5b.
[0081] Then, the full heating operation will be explained in
conjunction with FIG. 10. In the full heating operation in this
embodiment, the expansion machine 5a is not used, so that the
pre-expansion valve 6 and the bypass valve 7 are closed. Also,
although the number of the outdoor heat exchangers 3a, 3b and 3c
that serve as evaporators can be adjusted by the open and close
operation of the electromagnetic valves 26, 27 and 28 of the
outdoor unit 100, in this embodiment, the explanation will be made
as to where the electromagnetic valves 27 and 28 are opened and the
electromagnetic valve 26 is closed. At this time, the
electromagnetic valve 29 is opened. Also, the electronic expansion
valve 20 in the shunt unit 300 is set fully closed, the valve 21 is
set fully opened, the electromagnetic valves 31, 33 and 35 are set
in the open state, and the electromagnetic valves 30, 32 and 34 are
set in the closed state.
[0082] In the full heating operation in this embodiment, the
four-way valve 2 in the outdoor unit 100 is set so that the first
port 2a and the second port 2b communicate with each other and the
third port 2c and the fourth port 2c communicate with each other.
In this case, the depressurizing function is realized by the
electronic expansion valves 8a, 8b and 8c.
[0083] At this time, the refrigerant compressed by the first
compressor 1 to the supercritical state at the high temperature and
high pressure state flows into the shunt unit 300 from the third
port 2c to the fourth port 2d of the four-way valve 2 via the check
valve 92 and the high pressure pipe 63 because the check valve 90
is closed. The refrigerant flowed into the shunt unit 300 passes
through the electromagnetic valves 31, 33 and 35 and flows into the
indoor units 200a, 200b and 200c because the electronic expansion
valve 20 is closed. The high temperature high pressure refrigerant
flowed into each of the indoor units flows into the indoor heat
exchangers 9a, 9b and 9c to radiates heat to the indoor air to heat
the room to decrease the temperature. This refrigerant at the
intermediate temperature and high pressure is depressurized by the
electronic expansion valves 8a, 8b and 8c and flows into the low
pressure pipe 64 via the electronic expansion valve 21. The
refrigerant passes through the low pressure pipe 64 flows into the
electromagnetic valves 27 and 28 and the check valve 97. The
refrigerant flowed into the electromagnetic valves 27 and 28 and
the check valve 97 flows in parallel through the first to the third
outdoor heat exchangers 3a, 3b and 3c and evaporates therein
because the check valve 93 is closed due to the pressure difference
in the outdoor heat exchanger. The refrigerant evaporated in the
second outdoor heat exchanger 3b and the third outdoor heat
exchanger 3c joins together at the heat exchanger outlet portion,
passes through the check valve 96 to be joined together with the
refrigerant flowing out from the first outdoor heat exchanger 3a
and flows into the electromagnetic valve 29. The refrigerant passed
through the electromagnetic valve 29 is returned to the suction
side of the first compressor 1 via the second port 2b and the first
port 2a of the four-way valve 2 because the check valve 94 is
closed due to the pressure difference in the outdoor heat
exchanger.
[0084] In the cooling dominant operation, the depressurization by
the expansion machine 5a is not carried out because the high
temperature high pressure gas is needed to be supplied to the
indoor unit required to carry out the heating operation. That is,
in this case, the operation is carried out with the four-way valve
2 in the same connection position as in the cooling operation and
with the bypass valve 7 of the expansion machine 5a fully opened.
In this embodiment, the description will be made in terms of the
case where the indoor unit 200a is required to achieve the heating
operation, and the remaining two indoor units 200b and 200c are
required to achieve the cooling operation. Also, the cooling
dominant operation in which the electromagnetic valve 27 is opened
and the electromagnetic valves 26, 28 and 29 are closed will be
explained. At this time, the electronic expansion valves 20 and 21
are set to be closed, the electromagnetic valves 30, 33 and 35 are
set in the closed state and the electromagnetic valves 31, 32 and
34 are set in the open state. The gas refrigerant at a high
temperature and a pressure flows from the third port 2c via the
second port 2b of the four-way valve 2 into the check valve 94
because the electromagnetic valve 29 is closed. The refrigerant
passed through the check valve 94 passes through the
electromagnetic valve 27 and the check valve 97 because the
electromagnetic valve 28 is closed, and the refrigerant passed
through the check valve 97 flows into the first outdoor heat
exchanger 3a and radiate heat therein because the electromagnetic
valve 26 and the check valve 93 are closed. On the other hand, the
refrigerant that dissipated heat in the second indoor heat
exchanger 3b flows through the check valve 96 and joins to the
refrigerant that dissipated heat in the first outdoor heat
exchanger 3a and passes through the fully opened bypass valve 7 and
flows into the high pressure pipe 63 because the electromagnetic
valve 29 and the pre-expansion valve 6 are closed.
[0085] Thereafter, the refrigerant flows into the shunt unit 300
from which the refrigerant shunted at the electronic expansion
valve 20 inlet portion is supplied to the indoor unit 200a where
the heating operation is required and the other refrigerant is
supplied to the indoor units 200b and 200c where the cooling
operation is required. The refrigerant passed through the
electromagnetic valve 31 flows into the indoor unit 200a where the
heating operation is required and dissipates heat in the indoor
heat exchanger 9a and depressurized to an intermediate pressure in
the electronic expansion valve 8a. The indoor units 200b and 200c
where the cooling operation is required receive the supply of the
refrigerant that passed through the electronic expansion valve 8a.
Thereafter, the electronic expansion valves 8b and 8c regulate the
distribution flow rate ratio for each heat exchanger and, after the
thermal load in the space to be air-conditioned is processed in the
indoor heat exchangers 9b and 9c, the refrigerant flows into the
low pressure pipe 64 via the electromagnetic valves 32 and 34, and
flows into the first compressor 1 via the check valve 90, the
fourth port 2d to the first port 2a of the four-way valve 2.
[0086] Thus, in this embodiment, the power recovery by the
expansion machine 5a is not performed during the cooling dominant
operation.
[0087] In the heating dominant operation, the high temperature and
high pressure gas must be supplied to the indoor unit where the
heating operation is required, so that the depressurization by the
expansion machine 5a is not performed and the pre-expansion valve 6
and the bypass valve 7 are closed. The connection state of the
four-way valve 5a for the heating dominant operation is similar to
that of the heating operation. In this embodiment, the description
will be made as the case where the cooling operation is required at
the indoor unit 200a and the heating operation is required at the
remaining two indoor units 200b and 200c. Also the heating dominant
operation where the electromagnetic valves 27 and 29 are opened and
the electromagnetic valves 26 and 28 are closed will be described.
At this time, the electronic expansion valve 21 in the shunt unit
300 is set at a degree of opening for providing a proper pressure
difference thereacross, the electromagnetic valves 30, 33 and 35
are set in the opened state, and the electromagnetic valves 31, 32
and 34 and the electronic expansion valve 20 are set in the closed
state. The gas refrigerant at a high temperature and a high
pressure discharged from the first compressor 1 flows through the
third port 2c and the fourth port 2d to flow into the check valve
92 because the check valve 90 is closed. The refrigerant flowed
through the check valve 92 flows into the high pressure pipe 63
because the pre-expansion valve 6 and the bypass valve 7 are
closed.
[0088] Thereafter, the refrigerant flows into the shunt unit 300
and the refrigerant shunt at the inlet portion of the electronic
expansion valve 20 is supplied to the indoor units 200b and 200c
where the heating operation is required, and the remaining
refrigerant is supplied to the indoor unit 200a where the cooling
operation is required. The refrigerant that passed through the
electromagnetic valves 33 and 35 flows into the indoor units 200b
and 200c where the heating operation is required and dissipate heat
in the indoor heat exchangers 9b and 9c and is depressurized to an
intermediate pressure at the electronic expansion valves 8b and 8c.
On the other hand, the indoor unit 200a where the cooling operation
is required is supplied with one portion of the refrigerant that
passed through the electronic expansion valves 8b and 8c. The
remaining refrigerant passes through the electronic expansion valve
21 and flows into the low pressure pipe 64. The refrigerant that
passed through the electronic expansion valve 8a, after handing the
thermal load in the space to be air conditioned in the indoor heat
exchanger 9a, passes through the electromagnetic valve 30, and
joins with refrigerant in the gas/liquid phase flowing out from the
electronic expansion valve 21.
[0089] The refrigerant passed through the low pressure pipe 64
flows through the check valve 91 and flows into the check valve 91
and flows into the check valve 97 and the electromagnetic valve 27.
The refrigerant that passed through the check valve 97 flows into
the first outdoor heat exchanger 3a and evaporate therein because
the electromagnetic valve 26 and the check valve 93 are closed. The
refrigerant evaporated in the second indoor heat exchanger 3b flows
through the check valve 96 and is joined to the refrigerant
evaporated in the first outdoor heat exchanger 3a and, because the
pre-expansion valve 6 and the bypass valve 7 are closed, flows
through the electromagnetic valve 29 and from the second port 2b to
the first port 2a of the four-way valve 2 and into the first
compressor 1.
[0090] Thus, in this embodiment, the power recovery by the
expansion machine is not performed
[0091] In this embodiment, in the full cooling operation where the
expansion machine is utilized, the heat transfer area of the
outdoor heat exchanger disposed on the suction side of the second
compressor 5b is controlled in accordance with the environmental
conditions to realize a high efficiency operation. For example,
when the outdoor temperature is increased as shown in FIG. 8
showing the first embodiment, the heat radiator outlet temperature
is increased and the expansion power is increased, so that the
operation is achieved in the direction of opening the on-off valve
6 which is the pre-expansion valve or the on-off valve 7 which is
the bypass valve (toward the decreased rotational number), and when
the outdoor temperature is decreased, the heat radiator outlet
temperature is decreased and the expansion power is decreased, so
that the operation is achieved in the direction of closing the
on-off valve 6 or the on-off valve 7 is closed (toward the
increased rotational number).
[0092] Accordingly, in this embodiment, when the outdoor
temperature is decreased, utilizing the relationship shown in FIG.
8, the heat transfer area of the outdoor heat exchanger on the
suction side of the second compressor 5b (number of the outdoor
heat exchanger) is decreased by the on-off operation of the
electromagnetic valve, and the loss of the recovered power at the
on-off valve 7 which is the pre-expansion valve can be decreased.
On the other hand, when the outdoor temperature is increased, the
heat transfer area of the outdoor heat exchanger on the suction
side of the second compressor 5b (number of the outdoor heat
exchanger) is increased, and the loss of the recovered power at the
on-off valve 7 which is the pre-expansion valve can be decreased.
This control concept is applicable not only when the outdoor
temperature is changed, but also when the indoor temperature or the
air conditioning load is changed.
[0093] From the above, it is understood that, in accordance with
the environmental conditions such as the outdoor temperature,
indoor temperature and air conditioning load, the heat transfer
area (number of outdoor heat exchanger used) of the outdoor heat
exchanger on the suction side of the second compressor 5b is
increased or decreased to minimize the recovered power loss at the
expansion machine 5a, enabling an efficient operation of the
refrigeration cycle device.
[0094] It is to be noted that the method for controlling the
flowing refrigerant flow rate and the recovered power utilizing the
bypass valve 7 and the pre-expansion valve 6 disposed at the inlet
portion of the expansion machine 5a is similar to that of the first
embodiment, so that the detailed explanation thereof is
omitted.
[0095] From the above, it is understood that, in the refrigeration
cycle device where the cooling operation and the heating operation
can simultaneously be achieved, by achieving the power recovery
operation by the expansion machine only in the full cooling
operation mode, and by increasing and decreasing the heat transfer
area of the outdoor heat exchanger on the suction side of the
second compressor 5b in accordance with the environmental
conditions such as the outdoor temperature, the indoor temperature
and the air conditioning load, the loss in the recovery power can
be minimized, enabling an efficient operation of the refrigeration
cycle device. While the transfer area is changed at the suction
side of the second compressor 5b in this embodiment, the
arrangement may be such that the heat transfer area at the
discharge side of the second compressor 1 is changed to change the
inlet density of the expansion machine 5a. Also, in stead of
increasing or decreasing the heat transfer area, the arrangement
may be such that the air flow rate to the outdoor heat exchanger
may be increased or decreased.
Embodiment 3
[0096] The description will now be made as to the refrigeration
cycle device according to the third embodiment shown in FIGS.
11-16. The third embodiment differs from the first embodiment that
the expansion machine unit has formed therein a second compression
discharge pressure space and the outlet side of the bypass circuit
is connected to the second compression discharge pressure space.
This structure allows the fluid flowing through the bypass circuit
to always flows into the refrigeration circuit via the second
compression discharge pressure space.
[0097] FIG. 11 is a schematic diagram of the refrigeration cycle
device according to the third embodiment of the present invention
and FIG. 12 is a view showing the detailed structure of the
expansion unit according to the third embodiment of this invention.
In the figures, the same reference numerals designate the same or
identical components, and this applies equally to the entire
application.
[0098] In the refrigeration cycle device according to this
embodiment, the outdoor unit 100 disposed outdoor has contained
therein the first compressor 1 for compressing the refrigerant gas,
the four-way valve 2 and the four-way valve 4 which are refrigerant
flow path change over means for changing the flow of refrigerant
according to the operational mode of the indoor units 200a and
200b, the first outdoor heat exchanger 3a and the second outdoor
heat exchanger 3b which serves as a heat radiator or an evaporator
according to the operational mode, and an unillustrated blower for
forcedly supplying outdoor air to the outer surfaces of the first
outdoor heat exchanger 3a and the second outdoor heat exchanger
3b.
[0099] The expansion machine unit 50 is provided therein with the
expansion machine 5a and the second compressor 5b and they are
coaxially connected. The second compressor 5b is provided with a
bypass circuit formed by external piping and a bypass valve 53
which is a check valve as the on-off valve in the bypass circuit,
the outlet end of the bypass circuit being connected to the
expansion machine unit 50. Other components constituting the
refrigeration cycle and the control method therefore are similar to
those of the first embodiment, so that the detailed description is
omitted.
[0100] FIG. 12 shows the structure of the expansion machine unit 50
of the refrigeration cycle device shown in FIG. 11, both the
expansion machine 5a and the second compressor 5b being in the
scroll type structure. The hermetic vessel 310 of the expansion
machine unit 50 has installed at the lower portion of thereof the
expansion machine 5a, and above the expansion machine 5a the second
compressor 5b. The expansion machine 5a is composed of an expansion
machine stationary scroll 351 and an expansion machine orbiting
scroll 352, and the second compressor 5b is composed of the second
compressor stationary scroll 361 and the second compressor orbiting
scroll 362. At the center of these scrolls, a shaft 308 is
penetrated, the shaft 308 has disposed at its both end portions
balance weights 309a and 309b, and the shaft 308 is supported by an
expansion mechanism side bearing portion 351b and a second
compression mechanism side bearing portion 361b. The expansion
mechanism side scroll 352 and the second compression mechanism side
scroll 362 are of the back-to-back structure or the integral
structure wherein they have a common base plate. The orbiting
scroll has disposed at its central portion a crank portion 308b for
eccentrically drive the orbiting scroll, and on the second
compression mechanism side an Oldham ring 307 for restricting the
rotation of the orbiting scroll.
[0101] At the bottom end of the shaft 308, an oil supply pump 306
is mounted, and an oil supply bore 308c is formed in the shaft 8.
On the outer circumference portions of the stationary scroll 351
and the stationary scroll 361, an oil return bore 317 is formed to
extend from the upper space 370 of the stationary scroll 361 and
not communicated with the orbiting scroll moving space 371, and a
lubricating oil 318 is stored in the lower space 372 of the
stationary scroll 351.
[0102] In the bottom portion of the hermetic vessel 310 in which
the lubricating oil 318 is stored, an oil pipe 380 for
communicating the first compressor 1 with a position higher than
the optimum oil level or the bottom surface of the hermetic vessel
310.
[0103] At the outer circumference of the expansion mechanism 5 and
at the side surface of the hermetic vessel 310, an expansion
suction pipe 313 for suctioning the refrigerant and an expansion
discharge pipe 315 for discharging the expanded refrigerant. On the
other hand, above the second compressor 5b and at the upper surface
of the hermetic vessel 310, a second compression suction pipe 312
for suctioning the refrigerant is disposed. Above the stationary
scroll 361 of the second compressor 5b and at the side surface
within the hermetic vessel 31, a bypass pipe 316 connected to the
bypass valve 53 and a second compression discharge pipe 314 for
discharging the compressed refrigerant are disposed.
[0104] In the expansion machine 5a, the base plate 351a of the
stationary scroll 351 has formed therein an expansion suction port
351d for suctioning the refrigerant and it is connected to the
expansion suction pipe 313. At the tip ends of the scrolls 351s of
the stationary scroll 351 and the expansion mechanism side scroll
352 of the orbiting scroll, tip seals 354 are attached for sealing
the second compression chamber 353 defined by the scroll 351s of
the stationary scroll 351 and the expansion mechanism side scroll
352 of the orbiting scroll.
[0105] In the second compressor 5b, the base plate 361a of the
stationary scroll 361 has formed therein a second compression
suction port 361d for suctioning the refrigerant and a second
compression discharge port 361e for discharging the refrigerant,
the second compression suction port 361d being connected to the
second compression suction pipe 312. At the tip ends of the scrolls
361s of the stationary scroll 361 and the second compression
mechanism side scroll 362 of the orbiting scroll, tip seals 364 are
attached for sealing the second compression chamber 363 defined by
the scroll 361s of the stationary scroll 361 and the second
compression mechanism side scroll 362 of the orbiting scroll. Also,
at the outer circumference and in the surface opposing to the
orbiting scroll, an outer circumference seal 365 for sealing
between the orbiting scroll and the stationary scroll 361 is
provided.
[0106] FIG. 13 is a plan view showing the second compressor 5b
according the third embodiment of the present invention, which
shows a combination of the second compression mechanism side scroll
362 of the orbiting scroll and the stationary scroll 361. The
second compression suction port 361d is disposed in a position not
interfering with the outer end portion of the second compression
mechanism side scroll of the orbiting scroll, and a space defined
between the outermost circumferential wall of the second
compression chamber 363 and the outer seal 365 disposed on the
stationary scroll 361 is the suction pressure space 374 for the
second compressor 5b.
[0107] Then, the operation of the expansion machine unit 50 will be
described. FIG. 14 is a view illustrating the flows of the
refrigerant gas and the oil in the second compressor of the third
embodiment of the present invention.
[0108] The power is generated by the expansion of the high pressure
refrigerant suctioned from the expansion suction pipe 313 within
the expansion chamber 353 defined by the stationary scroll 351 and
the expansion mechanism side scroll 352 of the orbiting scroll. The
refrigerant expanded and depressurized within the expansion chamber
353 is discharged via the orbiting scroll movement space 371 from
the expansion discharge pipe 315 to outside of the hermetic vessel
310.
[0109] The refrigerant suctioned from the second compression
suction pipe 312 is compressed and pressurized within the second
compression chamber 363 defined by the stationary scroll 361 of the
second compressor 5b and the second compression mechanism side
scroll 362 of the orbiting scroll by the power generated at the
expansion machine 5a. The refrigerant compressed and pressurized
within the second compression chamber 363 is, after discharged into
the upper space 370 within the hermetic vessel 310, discharged to
the outside of the hermetic vessel 310 through the second
compression discharge pipe 314. At this time, the outer
circumference portion of the second compressor 5b and the orbiting
scroll movement space 371 is sealed by the outer circumference seal
365, so that the orbiting scroll moving space 371 is at an expanded
pressure, and the lower space 372 is at the compressed pressure of
the second compressor equal to that of the upper space 370 via the
oil return bore 317 that is not communicated with the orbiting
scroll moving space 371. The bypass valve 53 disposed exterior of
the hermetic vessel 310 is closed due to the pressure difference in
the second compressor 5b.
[0110] Then the behavior of the oil circulating together with the
refrigerant gas in the second compressor will now be described. The
oil suctioned into the second compressor 5b together with the
refrigerant gas from the first compressor 1 flows from the second
compression discharge port 361e into the upper space 370 through
the discharge valve 330. The oil flowed into the upper space 370 is
gas-liquid separated in the upper space 370 and collected at the
upper surface of the stationary scroll 361 and then returned to the
oil reservoir portion of the lower space 372 via the oil return
bore 317. The excessive oil stored in the lower space 372 is
returned to the first compressor 1 due to the pressure difference
between the first compressor 1 and the lower space 372 via the oil
pipe 380 disposed in the bottom portion of the hermetic vessel 310
to maintain the oil level at a proper level. Thus the above is the
operation when the pressure difference is generated within the
second compressor 5b.
[0111] Then the description will be made in terms of the operation
when there is no pressure difference in the second compressor 5b
(such as during the heating operation of the refrigeration system
using the expansion machine only during the starting up or cooling
operation or during the low rotation number operation). FIG. 15 is
a view showing one example of flows of the refrigerant gas and the
oil in the second compressor according to the third embodiment of
the present invention when no pressure difference is generated in
the second compressor 5b. At this time, the rotational number is
small, the suction flow rate is of the second compressor 5b is less
than the discharge flow rate of the first compressor 5a, the
suction pressure of the second compressor 5b is higher than the
compressed pressure, and the bypass valve 53 is in the open state.
The refrigerant gas discharged from the first compressor 1 is
divided and flows into a flow path in which it is suctioned by the
second compression suction pipe 312 and discharged into the upper
space 370 through the second compression chamber 363 and a flow
path in which it flows through the bypass pipe 53 and the bypass
pipe 316 into the upper space 370. Thereafter, it flows through the
second compression discharge pipe 314 and is discharged to the
outside of the hermetic vessel 310. The oil circulating together
with the refrigerant gas is also divided similarly to the
refrigerant gas into two flow paths and flows into the upper space
370. The oil flowed together with the refrigerant gas is separated
into gas and liquid within the upper space 370, stored on the upper
surface of the stationary scroll 361, and returned to the oil
storing portion in the lower space 372 via the oil return hole
317.
[0112] FIG. 16 is a view showing another example of flows of the
refrigerant gas and the oil of the second compressor according to
the third embodiment of the present invention when there is no
pressure difference in the second compressor 5b. At this time, the
second compressor 4b is not rotated and entire the refrigerant gas
and the circulating oil flowing in the refrigeration cycle device
flows in the bypass pipe 314 and flows into the upper space 370.
Thereafter, the refrigeration gas is discharged out of the hermetic
vessel 310 via the second compression discharge pipe 314. On the
other hand, the oil entrained in the refrigerant gas is separated
from the oil within the upper space 370, stayed on the upper
surface of the stationary scroll 361, and returned to the oil
reservoir portion in the lower space 372 via the oil return hole
317.
[0113] That is, in this embodiment, the excessive amount of the
flow is automatically bypassed by the bypass valve 53 and whole
amount of refrigerant gas and the circulating oil flowing through
the refrigeration cycle device is always passed through the upper
space 370 of the second compressor 5b and is separated into gas and
liquid in the upper space 370.
[0114] The oil supply mechanism in the expansion unit 50 will now
be described. When the shaft 308 is rotated by the expansion power
of the expansion machine 5a the oil supply pump 306 supplies the
lubricating oil 318 stored within the lower space 372 to the
bearing portions 361b and 352b and the crank portion 308b via the
oil supply bore 308c. Also, the oil leaked into the upper space 370
from the lubricating oil 318 supplied to the bearings 361b and 352b
as well as the crank portion is returned to the oil reservoir
portion in the lower space 372 via the oil return hole.
[0115] As for the thrust load acting on the orbiting scroll, the
orbiting scroll movement space in this embodiment is also at the
expanded pressure and is similar to the first embodiment.
[0116] According to the above structure, the oil separated within
the expansion machine unit 50 is moved between the first compressor
1 and the expansion machine unit 50 second directly to the first
compressor 1 without passing through the refrigerant cycle circuit,
so that the expansion machine unit 50 functions as an oil separator
for the first compressor 1, providing an advantageous effect that
the degrading of the heat exchanging performance due to mixture of
the oil into the refrigerant can be suppressed.
[0117] Also, because of the oil separating function of the
expansion machine unit 50 and the oil level regulating function of
the oil pipe 380, an optimum oil level can be always maintained in
the lower space 372, a stable oil supply to the bearing portion can
be established and the generation of the agitation loss due to an
excessive amount of oil can be prevented, so that the starting up
performance can be improved.
Embodiment 4
[0118] The refrigeration cycle device according to the fourth
embodiment of the present invention shown in FIGS. 17-19 will be
described. As has been described in conjunction with the
refrigeration cycle device shown in FIGS. 1-9, the COP improvement
ratio can be made maximum by setting the heat transfer area of the
second outdoor heat exchanger 3b to be 0.3-0.5 and the expansion
compression volume ratio to be 1.8-2.3 when the air speed
distribution in the column direction of the heat exchanger is
uniform. However, when the fan is mounted higher than the heat
exchanger, an air speed difference is generated in the column
direction of the heat exchanger, and the heat transfer performance
changes at each of the first outdoor heat exchanger 3a and the
second outdoor heat exchanger 3b, making the ratio of the heat
transfer area different from that provides the same performance as
that when the air speed distribution is uniform. Therefore, in
actually manufacturing the heat exchanger, the air speed
distribution in the column direction of the heat exchanger must be
taken into consideration.
[0119] It is now assumed that the air speed distribution in the
column direction of the heat exchanger is as shown in FIG. 17. This
is the case where, as shown in FIG. 18, the fan in the C section is
disposed in a position upper than the heat exchanger, the A section
positioned high in the heat exchanger is used as the second outdoor
heat exchanger, the B section positioned low is used as the first
outdoor heat exchanger, and with the air speed distribution in the
column direction of the heat exchanger taken into consideration,
the COP improvement ratio exhibits the local maximal at a heat
transfer area ratio of the A section of around 0.33 as shown in
FIG. 19. When it is assumed that the expansion machine mounted
circuit can be effectively utilized even at -4% of the local
maximal of the COP improvement ratio, the heat transfer area ratio
in the A section is preferably within a range of 0.13-0.45. As
understood from FIG. 17, when the fan is installed higher than the
heat exchanger, the heat transfer area ratio becomes smaller than
that where the air speed distribution is uniform since the air
speed in the heat exchanger is higher in the higher position.
Further, as shown in FIG. 18, by arranging the heat exchanger
integral or by dividing so that the fins are not common in the row
direction, the installation space of the heat exchanger can be made
small, and by installing the A section at the high position in the
heat exchanger, the heat transfer area of the A section can be made
small, enabling the cost reduction of the heat exchanger as
compared to the case where the first outdoor heat exchanger and the
second outdoor heat exchange are independently used.
Embodiment 5
[0120] When the fan in the C section is mounted higher than the
heat exchanger and the second outdoor heat exchanger A section is
disposed at a position lower than the first outdoor heat exchanger
B section as shown in FIG. 20, the relationship of the COP
improvement ratio relative to the heat transfer area ratio is as
shown in FIG. 21, wherein the COP improvement ratio is at its local
maximal when the heat transfer area ratio of the A section is about
0.50. Assuming that the expansion machine installation circuit can
be effectively utilized at the COP improvement ratio of -4% of the
local maximal of the COP improvement ratio, the heat transfer area
ratio of the A section should preferably be within the range of
0.32-0.60. By utilizing the A section disposed at a low positioned
in the heat exchanger as the second outdoor heat exchanger, the
pass number in the A section can be increased and the pressure loss
in the A section can be decreased. Further, by arranging the heat
exchanger in an integral structure or in a divided structure in
which fins are not common in the row direction as shown in FIG. 20,
the installation space for the heat exchanger can be made small as
compared to the case where the second outdoor heat exchanger and
the first outdoor heat exchanger are independently used, enabling
to reduce the cost of the heat exchanger.
Embodiment 6
[0121] Further, as shown in FIG. 22, when the fan of the C section
is mounted higher than the heat exchanger, the arrangement may be
such that the outdoor heat exchanger is divided in the row
direction and the second outdoor heat exchanger in the A section is
downstream of the first outdoor heat exchanger in the B section. By
positioning the second outdoor heat exchanger in the A section on
the downstream side, an opposing flow is established in which the
heat exchanging is achieved between the high temperature
refrigerant and air in the second outdoor heat exchanger in the A
section, and between the low temperature refrigerant and air in the
first outdoor heat exchanger in the B section.
[0122] Also, in this embodiment, the ratio of the heat transfer
area of the second outdoor heat exchanger relative to the total
heat transfer area of the outdoor heat exchanger is determined only
by the performance during the cooling operation. It is to be noted
that, when the outdoor heat exchanger is utilized as the evaporator
during the heating operation, the enthalpy difference between the
suctioned air and the refrigerant temperature corresponding
saturation moisture air (the enthalpy difference is the driving
temperature difference in heat exchanging because the heat
exchanger is in the moist state in the evaporator) is small, making
the effect of the heat transfer area ratio on the performance
small, so that the above heat transfer are ratio can be determined
only by the performance during the cooling operation.
[0123] Also, in this embodiment, the arrangement is such that the
first and the second outdoor heat exchangers are used even during
the heating operation. Through the use of the first and the second
outdoor heat exchangers shunted by the pipes, the pressure loss
generated when the refrigerant flows into the respective heat
exchangers can be decreased, and the refrigerant amount flowing
into the heat exchangers can be regulated by the length and the
diameter of the shunt pipes.
[0124] From the above, when the fan is mounted higher than the heat
exchanger and the air flow distribution in the column direction of
the heat exchanger is to be taken into consideration, the second
outdoor heat exchanger is disposed at a position higher than the
first heat exchanger, and the heat transfer area ratio of the heat
transfer area of the second outdoor heat exchanger relative to the
total heat transfer area of the heat transfer areas of the first
and the second outdoor heat exchangers is set at 0.13-0.45, and
when the second outdoor heat exchanger is disposed at a position
lower than the first outdoor heat exchanger, and the heat transfer
area ratio of the heat transfer area of the second outdoor heat
exchanger relative to the total heat transfer area of the heat
transfer areas of the first and the second outdoor heat exchangers
is set at 0.32-0.60, and when the outdoor heat exchanger is to be
divided in the row direction, the second outdoor heat exchanger is
positioned on the downstream side.
Embodiment 7
[0125] The cross-sectional shape of the heat exchanger may not be
U-shape as shown in figures and other shape such as the straight
line-shape as shown in FIG. 23. Also, the fan of the C section may
not be in the higher portion but may be on the side of the heat
exchanger. In the figure, the white arrow indicates the air flow
and the A section in the downstream is used as the second outdoor
heat exchanger and the B section is used as the first outdoor heat
exchanger.
[0126] In the embodiments heretofore explained, the expansion
machine 5a and the second compressor 5b is not limited to the
scroll type, but may be any type such as the rotary type, the screw
type, the reciprocating type, the swing type, the turbo type and
the like, and still similar advantageous results can be
obtained.
[0127] Also, the refrigerant in the refrigeration circuit has been
explained as being carbon dioxide, another refrigerant may be used.
As for the refrigerant that becomes the supercritical state, a
mixture of carbon dioxide and ether such as dimethyl ether,
hydrofluoroether, etc. may be used. Also, without being limited to
the refrigerant that becomes supercritical state, a refrigerant
that achieves heat exchange in the ordinary two-phase state such as
a refrigerant including no chlorine such as HFC410A, HFC407C and
the like and the conventional Freon family refrigerant such as R22,
R134a and the like, or a natural refrigerant such as hydrocarbon
may be utilized.
* * * * *